The Merkabah operates simultaneously as two distinct but related things: a mystical concept from Jewish antiquity (the divine chariot that carries the prophet to the heavenly throne) and a geometric form from sacred geometry (the star tetrahedron — two interlocking tetrahedra, one pointing up and one pointing down). These two meanings come from different historical traditions but have been woven together in modern esoteric teaching, most extensively in Drunvalo Melchizedek's Flower of Life work. Understanding both layers is essential.
As a geometric form, the Merkabah — or star tetrahedron — is a three-dimensional Star of David. Two tetrahedra (the simplest Platonic solid — four equilateral triangular faces) are interlocked at their centres, one oriented point-upward (the masculine, ascending principle) and one point-downward (the feminine, descending principle). The result is a perfectly balanced, perfectly symmetric form that points simultaneously in all directions — up, down and to each of the four cardinal points. It is the geometric expression of the interpenetration of complementary principles, the three-dimensional version of the Seal of Solomon.
The word Merkabah (מֶרְכָּבָה) derives from the Hebrew root rkb — "to ride" or "to drive." It means, most directly, chariot. In the biblical context, the Merkabah is the vehicle upon which God rides — the fiery chariot with four living creatures (the Chayot) and four wheels within wheels (the Ophanim) described in extraordinary and bewildering detail in Ezekiel's first chapter. The vision is among the most cryptic and most studied passages in all of Jewish scripture.